The objective of this research is to learn the detailed mechanism of action of various metal-activated and metalloenzymes. When an enzyme is activated by or contains a paramagnetic metal ion (Mn, Co, Cu, Fe), or interacts with a paramagnetic substrate analog, structural, kinetic and thermodynamic information can be obtained about the immediate environment or the paramagnetic center by electron spin resonance and by nuclear magnetic resonance studies of the solvent, the substrates and the protein. The most useful NMR parameter is a longitudinal relaxation time (T1) of the nuclei of the substrate since rapid and accurate determinations of T1 permit distance calculations in solution. At least an order of magnitude improvement in the accuracy and speed of T1 determination has been made possible by our use of Fourier transform NMR spectroscopy, and by the refinement of methods for measuring T1. Using the Fourier transform method for measuring T1 or protons, phosphorus, carbon and other atoms of substrates and enzymes, the structures of ternary complexes of several metal activated enzymes will be investigated. The enzymes under investigation catalyze the transfer of phosphoryl groups (pyruvate kinase, PRPP synthetase, P-enolpyruvate carboxylaseo nucleotidyl groups (RNA and DNA polymerases) and the polarization of carbonyl groups (aldolase). Hemoproteins are being studied by Dr. R.K. Gupta. We are also improving the instrumentation and techniues for NMR studies of biological systems. The purpose of studying a large number of enzymes is to seek general principles of enzyme chemistry which might be used ultimately to control the rate and course of enzyme reactions in vivo and in vitro. Our finding of a unique substrate conformation on DNA polymerase and the presence of ZN in DNA polymerases from four sources might conceivably provide a basis for the design of chemotherapeutic agents for malignant disease. BIBLIOGRAPHIC REFERENCES: Sloan, D.L. and Mildvan, A.S. NMR studies of the conformation of ATP on pyruvate kinase from rabbit muscle. J. Biol. Chem. 246, 2431 (1976). Gupta, R.K., Fung, C.H. and Mildvan, A.S. Cr(III) ATP as a paramagnetic probe to determine intersubstrate distances on pyruvate kinase. J. Biol. Chem. 246, 2421 (1976).